The gang organizes a surprise party for Howard and Marion's 20th anniversary as clips from previous episodes are shown.
| Name | Type | Role | |
|---|---|---|---|
| Arthur Silver | Writer | ||
| Bob Brunner | Writer | ||
| Karen Duitsman | Guest Star | ||
| Diana Hyland | Guest Star | ||
| Nancy Walker | Guest Star | ||
| Udana Power | Guest Star | ||
| Gary Epp | Guest Star | ||
| Charlene Tilton | Guest Star | ||
| Jennifer Shaw | Guest Star | ||
| Paulette Breen | Guest Star | ||
| Diana Canova | Guest Star | ||
| Jerry Paris | Director |